This application is a national stage of PCT International Application No. PCT/EP2006/007642, filed Aug. 2, 2006, which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2005 040 141.4, filed Aug. 25, 2005, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a column tube switch module and to a steering column arrangement having a column tube switch module.
Column tube switch modules are modules which are arranged on a column tube of a steering spindle in a motor vehicle. These modules are configured in such a way that they are fitted, for example, with steering column switches for flashing indicator lights.
The column tube switch module is generally attached to the steering spindle and arranged concentrically with respect to the column tube of the steering spindle. A centering device such as is described in DE 102 59 167 A1 can be provided for attaching such a column tube switch module to the spindle.
The DE 102 59 167 A1 centering device is equipped with a bearing that supports the column tube switch module being on the steering spindle. During the mounting process, a force directed coaxially to the longitudinal axis of the steering spindle moves the column tube switch module in the axial direction as far as an end position and automatically centered in the radial direction, for example a force acting on a steering wheel hub by means of a steering wheel screw. It is advantageous here that just one method step, specifically the application of a coaxially acting force, is sufficient to attach the switch module to the column tube. At the same time, the application of the axial force causes the switch module to be pulled against the steering wheel so that it is not possible for any axial movement to take place between the switch module and the steering wheel. In addition, rotation or tilting of the switch module can be virtually ruled out. This advantage also makes it possible, inter alia, to carry out fault free mounting of a steering angle sensor integrated into the switch module.
For a wide variety of driver assistance systems it is necessary to use high-resolution steering angle sensors. However, high-resolution steering angle sensors only supply data which can be used and evaluated if the tolerances between the steering wheel and steering column are kept sufficiently small. In conventional fabrication and mounting solutions, such as described, for example, in DE 199 33 049 A1, it is proposed to shorten the axial tolerance chain by positioning the rotating part of the steering angle sensor, here the code disc, closer to the bearing of the steering column in the column tube.
The disadvantage of this solution is the large number of parts which are able to be mounted in the actual vehicle so that propagation of a module is prevented. Furthermore, the stator which is not centered permits a comparatively large number of tolerances compared to the steering column and steering wheel. The tolerances result from the free bearing of the steering wheel sensor system in the module and the indirect driving of the steering angle sensor rotor.
The object of the invention is accordingly to make available a column tube switch module which can be manufactured cost-effectively, while at the same time making available a high-resolution steering angle sensor.
The column tube switch module has, for the purpose of minimizing the axial and radial tolerance chain, a stator which is secured radially to the column tube by a centering device when there is a force acting coaxially with respect to the steering column. A preferably high-resolution steering angle sensor is supported on this radially secured stator. The rotating part is deflected in accordance with the deflection of the steering wheel hub by means of a driver moving the steering wheel hub. As a result of the combination of the attachment of the steering wheel sensor to the stator of the column tube switch module and the driver, the components of the steering system are prevented from influencing the accuracy of the steering angle sensor. The distance between the column tube and the end of the steering spindle can be increased by virtue of the inventive attachment of the steering angle sensor to the stator without adversely affecting the axial tolerance chain.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying diagrams.